Pump piston



J. W. M CLATCHlE PUMP PISTON June 1, 1943.

Filed Oct. '7, 1940 INVENTOR. JOHN W. MACCLATCHIE BY fl g )u WcWa-J-2AATTORNEY.

Patented June 1, 1 943 PUMP PISTON John W. MacClatchiaLos Angeles,Calif., assignor to MacClatchie Manufacturing Company of California,Compton, Calif., a corporation of California Application October 7,1940, Serial No. 360,092

2 Claims.

This invention relates to pistons used in mud pumps and the like.

More particularly this invention relates to that 7 type of piston inwhich packing elements of resilient material are mounted on an axialsupport with an abutment projecting radially from the axial supportwhich forms a backing for the packing elements.

The object of my invention is to provide a means for sealing ofi saidpacking elements with respect to said abutment.

Another object of my invention is to provide a packing element having anannular groove adjacent the radially projecting abutment so that anyfluid leaking between the axial support and the packing element willexpand the side of said groove adjacent the abutment to provide a fluidtight seal between said abutment and said packing member.

Another object of my invention is to provide a piston which is capableof withstanding considerable use at high pressures.

My invention has many other objects, advantages, and features, some ofwhich, with the foregoing, will be set forth in the followingdescription where I shall outline one form of my invention, which I haveselected for illustration in the drawing accompanying and forming a partof the present specification.

Referring to the drawing Figure 1 is a side elevation of a pistonembodying the invention, partly in section.

Figure 2 is a section taken along the line 2-2 of Figure 1.

Figure 3 is a side view of a packing element in unassembled position,with a portion of the reinforcing flange cut-away.

The invention is illustrated embodied in a double acting piston, whichcomprises a hub I mounted on a piston rod II. A radial flange orabutment I2 projects integrally from the hub I0 intermediate the ends ofsaid hub. Mounted on the hub III on each side of flange I2 are packingelements I3, which may be formed of rubber or other suitable resilientmaterial. The flange I2 forms a longitudinal backing for each of thepacking elements I3. I prefer to reinforce the inner end II of thepacking element I3 with a metallic plate, fabric or other suitablematerial. As an instance of this arrangement a metallic plate I5 havinga flanged portion I6 is provided at the inner end of each packingelement I3.

The packing elements are secured on the hub III by follower plates I'I,I8 which are mounted on the piston rod II at the outer ends of thepacking elements I3. In the example 'shown, the follower plate I! iswedged on the piston rod as indicated at I9, the hub I0 is mounted onthe piston rod II and the follower plate I8 is secured on said rod bymeans of a retaining nut 20 and a lock nut 2I.

In order to provide a rigid backing for the packing element I3, I preferto have the outer radial ends 22 of the follower plates II, I8 extendout at least as far-and preferably further-,than

' the inner radial ends 23 of the reinforcement plates I5.

As shown in Figure 3,,I prefer to build up the lower portion 24 of theinner end I4 of the packing element I3 so that said lower portion'24forms an angle with the reinforcement plates I5. The purpose of thisadded material is to make certain that the rubber or other resilientmaterial adjacent the radial flange will be under compression in theassembled piston.

However, even though the portion 24 of the packing element I3 is undercompression in the assembled piston, I have found that when such apiston without additional means to seal off the inner end of the packingelement from the radial flange I2 is used in mud pumps operated at highpressures, thatfiuid passes between the hub I0 and the adjacent side 25of the packing element and between the inner end I4 of the packingelement and the radially projecting flange I2.

Means are therefor provided to positively seal oif the packing elementswith respect to the radially projecting flange I2 at all times andparticularly on the pressure side of the piston. As an instance of thisarrangement, the lower portions '24 of the packing elements 13 areprovided with annular grooves 26 adjacent the radial flange I2, thesides of which grooves adjacent the radial flange are adapted to beexpanded by fluid pressure to seal off said flange with respect to saidpacking members. Any fluid passing between the hub III and the adjacentside 25 of the packing element I3 which could otherwise escape betweenthe radial flange I2 and the inner end Id of said packing element I3 andthereby cutout and damage said parts, passes into one of the annulargrooves 26, thereby expanding the sides of said groove adjacent theradial flange I2 into fluid-tight engagement with said flange andsealing off said packing elements with respect to said flange.

I have found that pistons embodying the features of my invention havegiven excellent results, even when used on mud pumps operated atextremely high pressures.

From the foregoing description taken in connection with the accompanyingdrawing, the construction, operation, uses and advantages of myinvention will be readily understood by those skilled in the art towhich the invention appertains. While I have described the form of myinvention which I now consider to be the best embodiment thereof, Idesire to have it under-,

stood that the form shown is merely illustrative and that the inventionis not to be limited to the details disclosed herein, but is to beaccorded the full scope of the appended claims.

I claim:

1. In a pump piston, a hub, a radially projecting flange medial of thelength of said hub and flxed against longitudinal movement relativethereto, annular packing elements mounted on the hub with the radiallyprojecting flange forming a longitudinal backing for the packingelements, said packing elements having annular grooves adjacent saidradially projecting flange, the sides of said grooves adjacent saidradially projecting flange being adapted to be expanded by fluidpressure to seal of! said packing members and said flange and followersfor clamping said packing elements against said radially projectingflange.

2. In a pump piston, a hub, a radially projecting flange medial oi thelength of said hub and fixed against longitudinal displacement relativethereto, annular packing elements mounted on the hub with the radiallyprojecting flange forming a longitudinal backing for the packingelements, each of the inner ends of said packing elements havingreinforcement material, an enlarged portion adapted to be compressed onassembly to aid the sealing of said member with respect to said radiallyprojecting flange and an annular groove in said enlarged portion, thesides of said grooves adjacent said radially projecting flange beingadapted to be expanded by fluid pressure to seal off said packingmembers and said flange, and followers for securing the packing elementsagainst the radially projecting flange, the outer ends of said followersbeing at .least as far out radially as the inner ends of saidreinforcement material.

JOHN W. MACCLATCHIE.

